Rapid Test Developed for Inherited Immune Deficiency

Developed in the NHGRI Division of Intramural Research (DIR), the new test can use the same dried blood samples already collected from newborns and would provide the first accurate, high-throughput screen for immune deficiencies. Prior efforts to identify this disorder by counting white blood cells in newborns proved unreliable and expensive.

"This new laboratory technique is an excellent example of how increasingly sophisticated genetic tools can be applied to important public health problems," said NHGRI Scientific Director Eric D. Green, M.D., Ph.D. "Here we have a chance to catch an illness early when treatment is most effective. This new approach provides a rapid, accurate indication of a possible immune problem immediately after birth while the infant is protected by the mother's antibodies still circulating in the baby's blood."

The sooner a child is diagnosed, the sooner treatment can begin and the more likely it is to be effective. "Too many babies are diagnosed too late," said Jennifer M. Puck, M.D., chief of NHGRI's Genetics and Molecular Biology Branch.

"Our false positive rate was about 1.5 percent, which is too high to be practical for screening," Dr. Puck said. A baby with a positive test would need to be evaluated to see if he or she was actually sick; a false positive rate of 1.5 percent would mean three out of every 200 newborns would need further testing.

Although the availability of the test raises the question of whether states should begin using it on all newborns, Dr. Puck concluded that the new test is not quite ready for widespread use. It must first be validated. Because the new test is still experimental, it is not available to the general public and the cost has yet to be determined.